This invention relates to exhaust processors for filtering particulate matter from a combustion product, and particularly to an exhaust processor having a by-passable filter regeneration system. More particularly, the present invention relates to an exhaust processor assembly having a filter and filter bypass assembly situated in an upstream portion of a processor housing and a muffler situated in a downstream portion of the housing.
It is well known in the art to employ a diesel particulate trap which filters combustion product from an engine by passing the combustion product through a filter element or substrate to remove solid particles and pollutants before the combustion product is released to the atmosphere. These substrates must periodically be cleaned to restore functionality to the trap. Heat is applied to each substrate to burn and oxidize trapped carbon particles removed from the combustion product in the substrate. During this cleansing or "regeneration" it is advantageous to divert the combustion product through an auxiliary passageway bypassing the substrate to allow regeneration of the substrate by a burner or heat source.
One object of the present invention is to incorporate a muffler into an exhaust processor assembly to meet acceptable noise standards by attenuating exhaust noise and also to provide an obstacle to easy disablement of an exhaust filter in the assembly by tampering with the exhaust filter while leaving the muffler in a functioning state.
Another object of the present invention is to provide muffler means, situated in a flow passage bypassing an exhaust filter, for attenuating noise produced by the exhaust as it is diverted through the bypass flow passage during regeneration of the filter.
Yet another object of the present invention is to provide a single housing including means for treating a combustion product and means for attenuating noise from the combustion product during regeneration of the treating means.
Still another object of the invention is to house an exhaust filter, substrate, or other combustion product treatment means in one flow passage of an exhaust process or assembly and an acoustic muffling device or other noise attenuation means in a second flow passage of the exhaust process or assembly.
A further object of the invention is to divide an upstream portion of an exhaust processor housing into a first flow passage containing a substrate and a second flow passage bypassing the substrate and place a muffler in a downstream portion of the housing to receive combustion product from both of the first and second flow passages before the combustion product is discharged from the housing so that noise of combustion product conducted through either a main or substrate bypass passage is attenuated by a muffler in the housing.
A still further object of the invention is to provide a mixing region between a partition which cooperates with an inner wall of the housing to define first and second flow passages in the upstream portion of the housing and a muffler situated in the downstream portion of the housing to permit combustion product passing through the first and second flow passages to mix prior to entering the muffler so that the entire spatial volume of the muffler can be utilized by combustion product passing through either the first or second flow passage.
An additional object of the present invention is to provide a substrate for filtering combustion product in an internal flow Passage spaced apart from the wall of the housing so that combustion product from an engine flows evenly around the substrate to reduce thermal stresses in the substrate, thereby reducing the risk of failure of the substrate.
According to the present invention, an exhaust processor assembly includes a housing having an inlet for introducing combustion product into the housing and an outlet for discharging the combustion product from the housing. A partition is positioned within the housing to divide an upstream portion of the housing located in close proximity to the inlet into at least two regions. A substrate is situated in a first region. The substrate collects particulate matter entrained in the combustion product as the combustion product passes through the first region. A muffler is situated in a downstream portion of the housing in close proximity to the outlet to attenuate noise generated by combustion product passing through the housing toward the outlet. The muffler is spaced apart from the partition.
In preferred embodiments, a top shell and a complementary bottom shell are joined together to form the housing. The partition includes an outer flange trapped between portions of the top and bottom shells to secure the partition in its position within the housing. The partition and the bottom shell cooperate to define the first region for housing the substrate, and the partition and the top shell cooperate to define the second region for bypassing the substrate during regeneration.
The muffler extends between the top and bottom shells to provide means for reversing the direction of combustion product flow to attenuate noise generated by the combustion product. The reversing means includes a plurality of baffles interconnecting the top shell and the bottom shell to define a plurality of chambers. At least two tubes are configured to interconnect selected chambers to define means for conducting combustion product through the muffler toward the outlet.
According to another preferred embodiment of the present invention, the partition includes an upper partition member and a lower partition member trapped between portions of the top and bottom shells. The upper and lower partition members cooperate to define the first region therebetween. The first region provides an internal flow passage through the upstream portion of the housing. The substrate extends between the upper and lower partition members to filter combustion product passing through the first region.
First and second bypass channels are formed inside the housing for directing combustion product from the inlet to the muffler without flowing through the first region during regeneration of the substrate. Valve means directs combustion product from the inlet into either the first region or the first and second bypass channels. The upper partition member and the top shell cooperate to define the first bypass channel and the lower partition member and the bottom shell cooperate to define the second bypass channel.
One feature of the present invention is the provision of a muffler situated in a downstream portion of a housing in a spaced apart relation from a partition which divides an upstream portion of the housing into at least two regions, one region containing a substrate for solid particle filtration and at least one bypass region to divert combustion product from the inlet to the muffler without passing through the substrate during regeneration. Advantageously, such a feature permits combustion product passing through any of the at least two regions to mix prior to entering the muffler so that the entire volume of the muffler can be utilized by combustion product passing through any of the at least two regions, thereby increasing sound attenuation of all the combustion product passing through the housing.
Another feature of the present invention is the provision of first and second partition members situated in a upstream portion of the housing and spaced apart from the wall of the housing to define an internal flow passage containing the substrate and first and second bypass channels. Advantageously, this feature provides substantially even temperatures along an outer surface of the substrate as combustion product passes from the engine through the first and second bypass channels to reduce the risk of cracking the substrate created when the substrate is exposed to large temperature variations along its outer surface.
In this specification and in the claims, the words "an exhaust processor" are intended to refer to various types of catalytic convertors and processors, diesel particulate filters, and other particulate traps in connection with which the invention may be used.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.